The present invention relates to a method and apparatus for recognizing an identifier that is entered into a system by a user, and in particular, to a method and apparatus that finds a match for such an input identifier from among a plurality of reference identifiers on the basis of a plurality of confusion sets.
Most institutions, such as banks and department stores, allow customers to access over the telephone a wide variety of services and account information. Before the advent of touch-tone telephones, a customer would obtain these services and information through interacting with a live operator. As touch-tone telephones became more prevalent in homes, these institutions began switching to automated customer-access systems. After dialing a telephone number, a customer using such systems would be asked to enter an account number or identifier. As used herein, the terms xe2x80x9caccount numberxe2x80x9d and xe2x80x9cidentifierxe2x80x9d are used interchangeably, and they refer to a string of characters that may comprise a plurality of letters, numbers, or both. Furthermore, as used herein, an identifier may be used not only to identify a user, but also may be used as an identifier for identifying a particular product or service offered by an institution. In the first generation of automated customer-access systems, a user would enter such an identifier by sequentially pressing a series of keys provided on the telephone keypad. Each pressed key would correspond to a different character in the identifier. The pressing of these keys would produce a series of tones that would be provided over a telephone network to the institution. At the institution, the series of tones would be decoded to produce the entered identifier, and if the identifier entered by the user was determined to correspond to a valid identifier, then the user would be allowed to enter commands, again through the telephone keypad, that would provide access to whatever services would be offered by the institution.
The next generation of automated customer-access systems eliminates the use of telephone keypads to verify the identity of a valid user. Had of entering an identifier through a telephone keypad, a user would be prompted to speak the identifier into the telephone handset. For example, the user may speak into the telephone the identifier xe2x80x9cJB123Exe2x80x9d. The user""s voice signal would be transmitted over the phone lines to the financial institution, which would employ a speech recognition system to produce a recognized identifier that is intended to correspond exactly to the identifier spoken by the user.
Nevertheless, such exact correspondence is quite difficult to attain, mostly due to the deterioration of voice signals that routinely occurs over conventional telephone lines. In particular, as a voice signal is transmitted to a remote location, conventional telephone lines introduce into such signals noise and restrictive band limitations. Such a deterioration present in a voice signal may cause a remote speech recognizer to produce a recognized output that does not correspond to the spoken identifier. Because of the limitations introduced into the voice signal by the telephone lines, the speech recognizer may confuse similar sounding letters and numbers. Thus, a speech recognizer may confuse the letter xe2x80x9cAxe2x80x9d with the number xe2x80x9c8xe2x80x9d, the letter xe2x80x9cKxe2x80x9d, or the letter xe2x80x9cJxe2x80x9d. Similarly, the speech recognizer may confuse the letter xe2x80x9cCxe2x80x9d with the letter xe2x80x9cDxe2x80x9d or the number xe2x80x9c3xe2x80x9d. For example, given that a user speaks the identifier xe2x80x9cJB123Exe2x80x9d into a telephone, the speech recognizer may produce xe2x80x9cAE123Dxe2x80x9d as an output. Accordingly, a need exists to enhance the accuracy of such speech recognition systems and overcome the limitations introduced into voice signals by typical communication lines, such as, for example, conventional telephone lines.
Similarly, touch-tone recognition systems also mistakenly recognize the wrong identifier. Accordingly, a need also exists to enhance the accuracy of such touch-tone recognition systems.
In order to overcome these deficiencies, the present invention is directed to a method and apparatus that enhances the reliability of a system intended to recognize multi-character identifiers provided by a remote user.
In a first representative embodiment of the present invention, the remote user enters an identifier by speaking into a voice input device. The present invention then provides a recognized identifier based on the entered identifier, the recognized identifier comprising a second plurality of predetermined characters. The present invention stores a plurality of reference identifiers, each one of the plurality of reference identifiers comprising a different plurality of predetermined characters. The present invention selects a match for the input identifier from this plurality of reference identifiers. The present invention also provides a plurality of confusion sets, each confusion set grouping together a different plurality of character members. The present invention compares each character in the recognized identifier with a character in a corresponding character position of each reference identifier to determine which characters in the recognized identifier do not correspond to characters in corresponding character positions of the reference identifiers. If a character in the recognized identifier does not match the character in the corresponding character position of a recognized identifier, the present invention eliminates the reference identifier if the non-matching characters are not from the same confusion set. After performing this comparison for every reference identifier, the present invention determines how many non-eliminated reference identifiers remain. If more than one such reference identifiers remain, the present invention will prompt the user with each remaining reference identifier until the user provides a positive confirmation that a particular reference identifier matches the input identifier. Alternatively, the present invention assigns an associative weighting to each remaining reference identifier and selects the reference identifier with the highest associative weighting as matching the input identifier. If only one reference identifier remains after the elimination operation, then that sole remaining reference identifier is selected as matching the input identifier.
According to yet another representative embodiment, the present invention is implemented in a touch tone recognition system. In this embodiment, a user enters an identifier through a conventional keypad of a touch-tone telephone. The system includes any suitable touch-tone recognizer for producing a recognized identifier, and the present invention selects a matching reference identifier for the input identifier entered in this manner according to the same operation discussed above.